Oktokit.js caching snippet in 2025

fetch-and-cache.ts

/**
 * This Gist shares a snippet of caching solution for Oktokit.js
 * In essense this defines a custom fetch function that wraps native fetch with caching,
 * where it stores cache in filesystem with path ./cache/<md5 of url>.json.
 * Inspired by https://github.com/octokit/octokit.js/issues/215.
 */
import crypto from 'crypto'
import { existsSync } from 'node:fs'
import { writeFile, readFile } from 'node:fs/promises'
import { Octokit } from '@octokit/core'

main().catch((err) => (console.error(err), process.exit(1)))

async function main() {
  const octokit = new Octokit({
    auth,
    request: {
      fetch: fetchAndCache
    }
  })

  // Access GitHub server first. Next time it doesn't and returns cached JSON response.
  await octokit.request('GET /repos/{owner}/{repo}/actions/runs/{run_id}/attempts/{attempt_number}', {
    owner: "xxx",
    repo: "xxx",
    run_id: "xxx",
    attempt_number: "xxx"
  })
}

async function fetchAndCache(url: any, options: any) {
  const key = md5(url)
  const path = `./cache/${key}.json`
  if (existsSync(path)) {
    console.info(`Cache hit: url=${url}`)
    const cache = await readFile(path, 'utf-8')
    return {
      status: 200,
      url,
      headers: new Map([
        ['content-type', 'application/json']
      ]),
      text: () => Promise.resolve(cache)
    }
  } else {
    console.info(`No cache hit: url=${url}`)
  }

  const res = await fetch(url, options)
  if (!res.ok) return res

  const cache = await res.text()
  await writeFile(path, cache)
  return Object.assign(res, {
    text: () => Promise.resolve(cache)
  })
}

function md5(string: string) {
  return crypto.createHash('md5').update(string, 'utf8').digest('hex')
}